The invention relates to eyewear frames and more specifically one whose front and rear surface curvatures remain substantially the same as their initial extruded curvature for the finished eyewear frame that has been cut out of an extruded billet of rigid material.
Eyewear frames encompass goggle frames, eyeglass frames and sunglasses frames. Most of the prior art eyewear frames are made of flexible plastic material. The lenses of these eyewear frames are normally flexed when installing them thereby producing internal stresses in the lenses and sometimes in the frames themselves. A major disadvantage of these assembled eyewear members is the fact that the stresses produce distortion in the lenses and the images viewed through the lenses are distorted. The use of metal frames for eyeglasses has been used for years. However these frames are not very strong and definitely not rigid and are often bent during use, when dropped, or by sitting or stepping on them. They are also rarely used with flexible plastic lenses.
About ten years ago an attempt was made to produce a rigid frame by forming it out of cast aluminum. This eyewear frame was the Briko snow ski goggle. It had a very thin flexible lens that had to be bent for insertion into the eyeframe and this curvature caused distortion of the images viewed by the wearer. Also its retention wall was very thin and often a blow to the frame caused the lens to pop out of the frame. It was definitely not a good design for impact type activities.
No one has designed and made a substantially rigid eyewear frame by using an extrusion process. Some of the applications for a rigid eyewear frame having a lens that would not pop out easily would be for paintball participants, military police, swat teams, the firearms shooting market, etc.
The Wilson U.S. Pat. No. 5,583,583 is directed to a metal frame for sunglasses and the method of making the same. A flat sheet of metal was cut in the predetermined shape of a sunglasses frame and it was heat treated in an annealing process to allow the frame to be bent into a predetermined concave curvature. It was heat treated to harden the material of the frame. An undesirable trait of this sunglass frame was that it would flex causing distortion of the lens and this was undesirable. Also when bent, the resulting radius was not constant.
It is an object of the invention to provide a novel rigid eyewear frame that can be used for goggles, eyeglasses and sunglasses.
It is also an object of the invention to provide a novel eyewear frame that begins as an extruded rigid billet of material such as metal or plastic.
It is also an object of the invention to provide a novel eyewear frame that has a rigid frame for receiving stress free lenses.
It is another object of the invention to provide an novel eyewear frame whose final configuration is substantially stress free since its curvature still remains substantially the same as when it was extruded.
It is a further object of the invention to provide a novel eyewear frame that has been designed for high impact activities and which has been designed so that its lens will not pop out easily upon impact.
It is also an object of the invention to provide a novel eyewear frame having structure that allows a stress free lens to be removably inserted therein and remain distortion free.
The novel method of manufacturing a stress free eyewear frame begins with the step of extruding a billet of rigid material from the extrusion die of an extrusion machine. The material could be a rigid aluminum alloy, a rigid titanium alloy, a hard plastic such as polycarbonate or other such acceptable materials having a petroleum base. If the material is a metal it would need a Rockwell hardness in the range of 20-110C. If the material is plastic it would have a Rockwell hardness in the range 80-130A.
As the billet of material is extruded, it has a top surface having a predetermined convex cross-sectional initially as extruded curvature and a bottom surface having a predetermined concave cross-sectional initially as extruded curvature. The length of the extruded billet could be as short as necessary in order to cut out only a single eyewear frame or it could be an extremely long, 50 feet or more, for cutting out multiple eyewear frames.
A predetermined length of the extruded billet would be attached to the holding fixture of a CNC machine capable of movement about at least 4 axes or as many as five axes. The CNC machine would have a turret head mill having a cutter mounted on one of its heads for milling the aperture of the eyewear frame. Another groove cutter would be mounted on another head for forming the groove in the lens aperture for receiving the lens. A cutter mounted on a mill head would also be used to cut the outer configuration of the eyewear frame. The eyewear frame would be substantially in its finished condition when it is removed from the holding fixture of the CNC machine or could be slightly altered by a bending press. Any small tab structure or rough edges along the outer edge of the eyewear frame can be easily removed. The resulting front surface of the finished eyewear frame would have the same predetermined convex cross-sectional initially as extruded curvature that it had in the initially extruded sheet. Likewise the rear surface of the finished eyewear frame would have the same predetermined concave cross-sectional initially as extruded curvature as found in the initially extruded sheet. Thus an eyewear frame has been produced free of any internal stresses such as would normally be found when forming an eyewear frame that requires a bending step to bring it to its final curvature. The eyewear frame could also be formed with two lens apertures.